This invention relates to integrally formed stamped sheet-metal blades having 3D structure and particularly to 3D metal working blades for an impeller or diffuser of centrifugal pumps and blowers.
Conventional impellers and diffusers used in pumps or blowers are generally made by casting or metal working. Products made by casting usually are bulky and heavy, have poorer material properties and often create a pollution problem in the production process, hence have gradually been replaced by metal working products.
3D metal working blades and vanes may be formed with accurate curved profile and have improved fluid passage and loading distribution, and may result in enhanced pumping efficiency. They are therefore widely used in high efficiency centrifugal pumps nowadays.
However conventional metal working technique cannot produce integral blades or vanes with accurate 3D curved profile. Each blade has to be produced one piece at a time separately, then be positioned and soldered individually between the front and rear covers of the impeller to form a complete impeller or diffuser. The production cost is high, and production time and process are long and tedious. It is because accurate 3D curved profile for the blades and vanes is difficult or impossible to make integrally by conventional stamping process.
Conventional stamping process now available can only produce integral forming blades or vanes of simple 2D profile for low priced products. It cannot make accurate 3D curved profile for the blades and vanes needed for high performance pumps and blowers.
To produce accurate 3D profile blades and vanes, the contemporary method is to make each blade and vane individually, then assemble the blades and vanes to form a complete impeller or diffuser. It needs a lot of different molds and jigs. Production cost is high. Assembly is difficult and costly.
Furthermore for some special purpose pumps such as those for improved de-swirl function or increased pumping pressure, they need impeller or diffuser of multi-row blades. U.S. Pat. Nos. 5,310,309, 4,877,370, 5,417,547, 5,516,263 and 4,354,802 have disclosed such examples. Multi-row blades mostly can only be produced by casting process to form the required 2D curve for creating desirable fluid passage and meeting loading requirement. To produce 3D metal working blades will greatly increase blades number. The cost of Production becomes too high. There are still rooms for improvement.
It is an object of this invention to provide integrally formed stamped sheet-metal blades having 3D structure that may substitute a plurality of individually made conventional blades to form a complete blades member by a relatively few number of assemblies and that have accurate 3D curved profile to enhancing pumping efficiency at a lower production cost and less production time.
It is another object of this invention to provide integrally formed stamped sheet-metal blades that may form a multi-row blades structure with accurate 3D curved profile for producing improved pumping efficiency at a lower assembly time and cost.
In one aspect, the integrally formed stamped sheet-metal blades having 3D structure of this invention includes at least two integrally formed blade members. Each blade member has a plurality of relatively short 3D curved blades and engaging means. The engaging means may facilitate positioning and engagement of the blade members to become a final and complete 3D curved blades or spaced multi-row blades assembly. As the complete 3D curved blade assembly is formed by a few number of relatively short blades the total blade number is greatly reduced. Molds and jigs needed are also reduced. Assembly and production become easier and faster. Production cost is lower. Multi-row blades structure by metal working process may become possible and less expensive.